This invention relates to a method of forming a pattern, and in particular, to a method of forming a pattern by making use of hybrid exposure, which is suited for the manufacture of a semiconductor device.
The photolithography has been widely employed in the manufacturing process of a semiconductor device because of its advantages such as processing simplicity and low cost. Owing to the continuous technological innovation, it is now becoming possible in recent years to miniaturize the semiconductor device of as small as not more than 0.25 xcexcm by making use of a light source of increasingly shortened wavelength (KrF excimer laser source). An ArF excimer laser source having a more shortened wavelength and a Levenson type phase shifting mask are now being developed with a view to further miniaturize the semiconductor element, so that these new technologies are expected to become a mass production lithographic tool which is applied to a device of 0.15 xcexcm rule.
However, there are still many problems that have to be solved before realizing the aforementioned new technologies in spite of the fact that it has already taken a long period of time for the development of these new technologies, so that it is feared that it may fail to catch up with the speed of the miniaturization of semiconductor device.
On the other hand, an electron beam lithography which is considered as one of the most prospective candidate for a post photolithography employs a finely throttled beam and has been proven to be useful for forming a pattern having a line width of 0.01 xcexcm.
This electron beam lithography, however, is accompanied with a problem in throughput as it is used as a device mass-production tool though no problem may be raised with respect to the miniaturization of device for the time being. Namely, since a fine pattern is required to be depicted one by one by turns, it inevitably takes a long time.
With a view to overcome this problem, there has been proposed a patterning method which is excellent both in resolution that can be attained by the employment of an electron beam exposure and in productivity that can be attained by the employment of a light exposure. Specifically, a resist which is sensitive to both ultraviolet rays and electron beam is employed in this patterning method, so that only the fine pattern to which ultraviolet rays can be hardly applicable with a sufficient margin is subjected to exposure using an electron beam, and the patterns other than the aforementioned fine pattern are to be exposed using ultraviolet rays, a resist thus exposed to ultraviolet rays being subsequently developed thereby to form a resist pattern.
However, according to the aforementioned patterning method, it has been difficult to obtain an excellent profile of pattern both in the pattern to be formed by making use of ultraviolet rays and in the pattern to be formed by making use of electron beam, because the distribution in intensity of ultraviolet rays differs from the distribution in intensity of electron beam. Furthermore, it becomes important in this patterning method to align at a high precision the position of the pattern that has been formed by making use of ultraviolet rays with the position of the pattern that has been formed by making use of electron beam.
However, according to the conventional method of aligning these positions with each other, the position of pattern that has been formed by making use of ultraviolet rays as well as the position of pattern that has been formed by making use of electron beam are both required to be corrected with reference to the alignment marks that have been formed in advance on the underlying substrate. Namely, an indirect alignment system has been adopted in the conventional method. Therefore, this conventional method is defective in that it is impossible to improve the alignment precision, because it is not designed to directly align these patterns with each other.
The present invention has been made under the circumstances, and therefore, an object of the present invention is to provide a method of forming a pattern, which is capable of forming a pattern having a high resolution specific to electron beam and capable of realizing an excellent productivity specific to light exposure, even if it employs a resist which is capable of forming an excellent profile when a light exposure is employed, but is incapable of forming an excellent profile when an electron beam exposure is employed.
Another object of the present invention is to provide a method of forming a pattern by making use of a hybrid exposure where patterns formed through light exposure and through electron beam are directly aligned with each other thereby making it possible to obtain a high precision alignment of these patterns.
Namely, according to this invention, there is provided a method of forming a pattern by making use of a hybrid exposure, the method comprising the steps of;
forming an underlying film on a work film;
forming a resist film on the underlying film;
exposing the resist film to a first energy beam of a first pattern;
forming a resist pattern by subjecting the resist film to a developing treatment;
exposing the underlying film to a second energy beam of a second pattern; and
dry-etching the underlying film with the resist pattern and the region of the second pattern of exposure by means of the second energy beam being employed as an etching mask.
According to this invention, there is also provided a method of forming a pattern by making use of a hybrid exposure, the method comprising the steps of;
forming a resist film on a work film;
exposing the resist film to a first energy beam of a first pattern;
forming a first resist pattern by subjecting the resist film to a developing treatment;
detecting information on the position of the first resist pattern;
exposing the first resist pattern to a second energy beam of a second pattern based on a result of the information obtained on the position of the first resist pattern; and
forming a second resist pattern by subjecting the first resist pattern to a developing treatment.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.